Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for maintaining a multimedia broadcast multicast service (MBMS) minimization of drive test (MDT) configuration in a wireless communication system.
Related Art
Universal mobile telecommunications system (UMTS) is a 3rd generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). A long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.
The 3GPP LTE is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.
The 3GPP LTE can provide a multimedia broadcast multicast service (MBMS) service. The MBMS is a service which simultaneously transmits data packets to multiple users. If a specific level of users exists in the same cell, the respective users can be allowed to share necessary resources so that the plurality of users can receive the same multimedia data, thereby increasing resource efficiency. In addition, a multimedia service can be used with a low cost from the perspective of users.
Minimization of drive tests (MDT) is a feature introduced in 3GPP LTE rel-10 to allow the harvesting of network coverage and quality information from customer user equipments (UEs) as they move within the coverage of the radio access network (RAN). This provides better quality data, at a lower cost, than that produced by the RAN operator performing drive testing of the RAN using test UEs.
The concept of MDT may be applied to MBMS, which may be referred to as MBMS-MDT. For a user equipment (UE) which is interested to receive MBMS or is receiving MBMS, MBMS-MDT may be configured and performed. The purpose of MBMS-MDT is allowing for the network operator harvesting of network coverage and quality information from UEs related to MBMS, which means that UEs can report areas in which MBMS cannot be received without enough quality. For configuration of MBMS-MDT, MBMS-MDT configuration may be provided by a network.
The MBMS-MDT configuration may be provided via system information. The system information is transmitted by cell-specific manner, i.e. only valid in a specific cell. Therefore, if a new cell, to which the UE is handed over, does not provide the MBMS-MDT configuration via system information, the previously configured MBMS-MDT should be discarded. However, considering the purpose of the MBMS-MDT, it may be required that the previously configured MBMS-MDT needs to be maintained in the new cell.